UNS S30908 is an austenitic stainless steel that combines excellent high temperature properties with good ductility and weldability. 309S is the ASTM designation for this material.UNS S30908 - Rolled Alloys, Inc.416 stainless steel is a free-machining martensitic stainless steel with 12-13% chromium that can be hardened by heat treatment to higher strength and hardness levels. In the annealed condition, it has, uns s30908 stainless steelAlloy 309 & 309S Stainless Steel, Great Plains Stainless309S (UNS S30908) stainless steel is the low carbon version of the alloy. It is utilized for ease of fabrication. 309H (UNS S30909) is a high carbon modification developed for enhanced creep resistance. It most instances the grain size and carbon content of